I never considered bougainvillea (that is the spelling

). I think it's more of a climbing plant and it is not as "woody" as what we are looking for. However, I guess it could technically be used if we used some posts and wires to guide it. Thanks for the suggestion, Maureen.
Druce, Leucaena (especially leucocephala) is abundant here and it has been promoted heavily for reforestation and soil conservation efforts, but the jury is out as to whether it can be useful as fodder for local cattle (due to the toxic mimosine content). If possible, I'd like for this fence to be multi-purpose, so using it for fodder and/or green manure is attractive (this is one reason I had originally considered moringa) but I'd hate to have it and then have to control cows and goats around it because they love it but can't digest it.
As for moringa, like I said before, I know it can be established in clay soils, but not with the time that I can give to the project for now. The property that I am working on is fairly far from where we currently live and we won't be moving to it for quite some time. I'm trying to prepare the land so that it is how we want it when we do finally get the chance to build and move. This means, at best, I'm a weekend landscaper, but more usually I'll only be able to follow up with projects on site monthly. My experience with moringa in clay doesn't seem favorable to that plan. I can do plenty of preparation of seedlings, etc. from home, but once its in the ground its practically on it's own.
Perhaps you know of a way that I could amend soil during planting to remedy that... Thanks so far. Please keep the ideas coming!